


Cuckoo

by ckret2



Series: No Kings Only Monsters (KOTM continuity / related oneshots) [22]
Category: Godzilla (2014), Godzilla - All Media Types, Godzilla: King of The Monsters (2019)
Genre: Adopted Sibling Relationship, Backstory, Canon-Typical Gore, Canon-Typical Violence, Gen, Godzilla & Mothra sibling relationship, I ported that to MonsterVerse and ran wild with it, Mild Gore, Origin Story, Pre-Canon, Reincarnation, Siblings, Sweetiefish, Symbiotic Relationship, Worldbuilding, specifically worldbuilding on how Godzilla & Mothra's species work, y'all remember how Godzillasaurus leave eggs in other species' nests in Heisei?
Language: English
Status: Completed
Published: 2019-11-04
Updated: 2019-11-04
Packaged: 2021-02-01 01:03:10
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 7,088
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21305465
Author URL: https://archiveofourown.org/users/ckret2/pseuds/ckret2
Summary: How Godzillas keep their young safe when there’s a plague of parasites that wants nothing more than to breed in their corpses; how Mothra’s miraculous rebirths are achieved with nothing more than a few DNA tweaks and a simple biological timer; and how a reincarnating moth and a radioactive lizard form a symbiotic relationship.
Relationships: Gojira | Godzilla & Mothra (Kaiju)
Series: No Kings Only Monsters (KOTM continuity / related oneshots) [22]
Series URL: https://archiveofourown.org/series/1483448
Comments: 9
Kudos: 100





	Cuckoo

**Author's Note:**

> Originally posted August 20.
> 
> This might be my best KOTM fic so far. Which is unexpected, since 90% of my KOTM fics so far star Ghidorah, but there you have it.
> 
> There's a lot of references to other continuities. Because a good large chunk of us currently writing KOTM fic came into fandom _because_ of KOTM and haven't seen all of the other movies yet, I explain the references to other continuities in the notes at the end.

“So, it’s like a bird’s entrusted egg.”

“What is this, ‘Bird’s Entrusted Egg’?”

“Entrusting an egg… Some birds will lay their eggs in the nest of another species when they can’t care for them.”

\- Professor Omae, discussing an unhatched Godzillasaurus egg found in a Pteranodon nest (_Godzilla vs. Mechagodzilla II_)

###

This was how nature worked:

The Godzillas ran. The Jinshin-Mushi hunted. The Godzillas fought alone. The Jinshin-Mushi fought together.

The Godzillas fell.

The Jinshin-Mushi bred.

###

Their species went by many names—phosphor mouths, starbacks, walking fish, screes. They went by many names because they didn’t claim any as their own, answering to whatever they were called by others. And worse names: death breaths, crocodile corpses, bug breeders, brood parasites.

Today, he was a brood parasite.

The brood parasite dragged himself onto the island, clutching his one surviving egg close to his chest. He spilled his own blood on the shore, so hot it sizzled where it hit the ground; he could feel stones tearing at the gaping hole in his abdomen, but couldn’t lift himself enough to keep from making his wound worse. It didn’t matter. He was dying soon anyway.

In his ruined abdomen he could feel the eggs the bug had put in him, nestled hard beneath his hide like tumors. He wished he’d had a chance to put his egg somewhere safe and get far away from it so the incubating bugs wouldn’t be able to go straight for his child when they hatched.

He wished he’d been able to put his egg in a nest that he knew he would accept it.

But he didn’t have that choice. This was the only nest he could reach. He’d just have to take a chance on the charity of an unproven species and die hoping.

He dragged himself to the nest’s narrow opening. Down through the hole, he could barely see the shell of the egg already occupying the nest. Carefully, he lifted his egg and slid it through the opening. His grip slipped. He watched with dread as his one egg rolled down the incline toward the other.

The slope evened out and the egg rolled to a gentle stop, right next to its new sibling.

There. He’d done the best he could for his child. He pushed more soil in front of the entrance, trying to make the opening a little less obvious. And then he turned and dragged himself back toward the ocean. The only thing he could do for his child now was get the bug eggs inside him as far from this nest as possible…

The brood parasite died on the shore.

And then he was just a bug breeder.

###

This was how nature worked:

Mothra was born alone, knowing everything.

Mothra grew wings.

Mothra circled the world, visiting her many nests. If a nest’s egg was broken or hatched, she laid another to replace it, its DNA encoded with her every memory up until the moment the soft shell closed around the newly-formed embryo. If a nest’s egg remained, she touched it with her telepathy, resetting its internal countdown to hatching, encoding her new memories into its DNA.

As long as a Mothra existed to check the nests, no egg would hatch.

Eventually, Mothra died.

The eggs’ timers counted down toward the day they were set to hatch.

One egg reached zero.

The egg hatched. Mothra was born alone, knowing everything.

The only species of titan that laid more eggs than Mothra was the Jinshin-Mushi. But, unlike Mothra, the Jinshin-Mushi formed swarms of innumerable parasites. They devoured the world alive.

There was only one Mothra. There was only ever one Mothra.

###

Hatching was like waking up after a long sleep, but far slower.

Hatching used to be terrifying—waking up without remembering having fallen asleep, being trapped in a small dark tight place. Mothra used to fear she’d die inside her shell without being able to tear free. So a long time ago, she’d rewritten herself from the inside—she could do that—so that her emotions felt different when she first began to wake up, so that the inside of a shell was no longer frightening.

At first she only changed one egg so that its future incarnation wouldn’t feel fear when she hatched. Changing herself like that was always dangerous, always carrying the risk that she’d do something wrong and cause the next incarnation to die; so she was cautious with such alterations and only experimented with one egg at a time.

But eventually that egg’s turn to hatch her reincarnation came, and she woke up healthy and safe and calm; and now all of her eggs carried the same change.

Not every egg faithfully recreated her the way it was supposed to. Sometimes the reincarnation that came out couldn’t lay eggs, and so he spent that generation protecting his existing eggs all the more fiercely, passing on his memories faithfully and waiting until he could reincarnate as herself again. Sometimes one egg carried two incarnations, and they would tumble into the world together in a confusion, and together she and herself would have to navigate being one person in two bodies—although, usually, one would be sickly and soon die, if not both. Sometimes she would hatch to find another reincarnation already alive, one that had mutated in its shell, one that was small and hard and sharp and mean, one that couldn’t speak to other minds and couldn’t mentally alter its own body and couldn’t speak to its eggs to reset their timers; and for a generation they would live together, and she would fear it would try to kill her.

But never, in all her lives, had she ever hatched from an egg to find a second one sitting next to her.

She stared at it, wondering if maybe she was somehow mistaking a large scrap of the eggshell she’d just ripped out of for an entirely separate egg. But no, it was definitely solid and whole—and it definitely _wasn’t_ one of hers. Had someone else dumped one of _their_ eggs in _her_ nest? The audacity! Did they see the opening to her burrow and think it was a convenient little nest they could steal without having to create their own? Or did they hope their child would hatch before she did and have a nice tasty egg to snack on for its first meal? She’d see about _that_.

With some difficulty, she tipped the hard egg onto its side and pressed her soft squishy new body against it to roll it up and out of her burrow. It radiated life and energy. The opening to her burrow crumbled as she shoved the egg through; she let the dirt and sand rain down on her.

Outside, she let the egg stop, crawled around it, and surveyed her island to see how best she could roll the egg out to sea and be rid of it.

There was a corpse on her island.

It was so massive—ten times her height—that half the meat had desiccated down to jerky before it could rot. A hip bone and broken ribs shone white where they stuck up out of the remains of the meat. In spite of the ancient body’s deterioration, she could still see how its abdomen had been ripped open. She could see the old, round shells of unhatched bug eggs.

Mothra stared in shock at the dead phosphor mouth. And then she looked at the egg.

She understood. She knew how phosphor mouths desperately tried to protect their children from parasites. They’d never tried to leave one with her before—her nests so cold and isolated, with a parent that only checked them every few years—but he’d had no choice.

Her nest was his child’s only chance.

She cleared the dirt away from the opening of the burrow, carefully rolled the egg back in, and set it back where she’d found it.

###

Her hatching must have awakened the phosphor mouth’s egg. Two days after she hatched, it started shaking; the day after that, she saw the first crack in its hard shell. That was probably how its species worked; the eggs must somehow know to hatch when their nestmates hatched, so that their adoptive parents would be more likely to see them as part of their brood. Were other species ever fooled by that, she wondered? She had seen families with a single phosphor mouth among them before, but she’d never known why the eggs hadn’t simply been kicked out of the nests like the brood parasites they were. Did other species, like her, pity the eggs?

Phosphor mouths ate her eggs sometimes. They weren’t the only species that did so, but they were one. She suspected strongly that sometimes they ate _her_. She rarely ever knew how she died, since she couldn’t pass the memories of her own death on to her eggs—but enough phosphor mouths had tried to eat her that she was sure some must have succeeded. She wasn’t their primary prey, but she _was_ their prey. She wondered whether the child inside this egg would know that.

This was an experiment, she supposed. An experiment to see whether she survived. An experiment to see whether a phosphor mouth left in the nest of its prey would see its fellow hatchling as family or food.

The next day, a chip tumbled off the side of the egg. Mothra carefully climbed the egg to peer inside the small hole.

A yellow eye peered back.

And then it was replaced by a snout, trying to poke its way through the hole, snorting and sniffing heavily. Its mind was only just waking up, but it was so curious that it made her feel curious too. She squished her face against the snout.

The phosphor mouth inside squeaked and jerked back. The egg shook as its center of balance shifted.

Mothra dropped back to the ground and left the egg alone.

###

Every once in a while, she’d see a muted blue glow from within the egg, accompanied by small yelps, as the phosphor mouth tried to blast its way free. She occasionally rapped on the egg encouragingly, just to let its occupant know that she was still there. Sometimes the occupant rapped back.

It took another two days for phosphor mouth to free himself. She was outside when it happened, but she heard the crackling shell, the thump, and the hatchling’s squeak of surprise. When she peered into her burrow, the hatchling was on his side, legs kicking, back plates flickering blue with alarm. He managed to roll onto his stomach and stayed there, flopped in the remains of his shell with his arms down at his sides and his chin on the ground. He was the same vivid green as the trees on her island.

_Hello_, she thought to him. He spasmed in surprise, got up to a sitting position, and stared up at her. He was too young to think in words yet—but he _felt_ excited to see her. He felt… attached to her.

That was a good sign. It meant that his species probably didn’t eat their nestmates. (What would she do if she was wrong, though—or, rather, what would her next incarnation do? If she died now, she wouldn’t be able to go to her other nests and pass on her memories, rewrite her eggs so that they’d know that they should smash any brood parasite eggs that made it into their nests. When her next incarnation came to the island to see how her egg was doing, would she see the two smashed eggs and the dead phosphor mouth and be able to tell what happened? She liked to think she’d be smart enough to draw the obvious conclusion.) She crawled down the burrow, and he crawled up to meet her, walking awkwardly on all four.

_I am Mothra_, she said as he sniffed her. _This is my island. You were left in my nest_.

Although he didn’t have words, she could feel a question in his mind: _Mother? Father?_ She could feel he wasn’t asking whether she had laid him—who had laid him was irrelevant to him, never entered his mind—he was asking who were the adults of this nest. Who was protecting them.

She hadn’t cocooned yet—she was stronger and lived longer if she waited before cocooning, and anyway she hadn’t wanted to be a bag of goo when the phosphor mouth emerge from his egg. _No adults_, she told him. _Just me, another hatchling._

For a moment, he was struck with terror at the thought—_No adults. No one to teach us or protect us._ But before she could try to reassure him, he pushed through the terror, studied her closely, and came to a decision.

_I will protect_, he concluded. _Sister._

Mothra was taken aback. He’d been out of his shell for only a few moments, he’d been confronted with the possibility that he was going to have to face the world all alone as a baby with only another baby beside him, and his first instinct was to become the other baby’s protector. Despite the fact that they weren’t even the same species! Despite the fact that, if he’d been a few decades older before meeting her, he would probably be trying to eat her.

_I can protect_, she told him. And he believed her with the whole-hearted faith with which babies always believed the thoughts she put in their heads. Too young to tell the difference between an inserted thought and an instinct.

And with all concerns about who was going to protect him gone, he wriggled past her—squishing into her side in the process—stumbled up the burrow, and emerged into the sun for the first time.

###

Phosphor mouths were cannibals, she discovered.

Almost as soon as he got outside, her new nestmate—her “brother,” she supposed—had spotted the corpse of his real parent, gleefully charged over on oversized feet, and started eating its neck.

Mothra stuck out her proboscis. Yuck. She’d do the same in an emergency, but she would never be so _happy_ about it.

He did it with such self-assurance that it _had_ to be an instinct. Maybe that was why the meat hadn’t rotted away but toughened in the sun, so it would last until the egg hatched? Maybe the adults expected to die and be fed to their children?

It had to happen a lot, considering that the adults were so likely to die before their children hatched that they’d made a habit of leaving their eggs in other nests.

With a strip of neck meat dangling from his mouth, the hatchling ran around the side of the corpse and dove into the ripped open abdominal cavity. Mothra stuck her proboscis out farther.

She heard a crackling sound, and then a crunching that was far larger than anything he could be biting. She crawled down beside the corpse, trying to see what the hatchling was doing.

He was eagerly kicking and tackling the bug eggs in his parent’s abdomen, collapsing them in on themselves, crushing their contents. His mind felt like he was playing. To him, this was a game he was born knowing how to play. Find the meat, eat the meat; find the eggs inside the meat, pop the eggs. It always amazed her how many different species were born ready to play games that would, someday, be turned into desperate fights for their lives. It was how they trained themselves, she knew. Even if nobody took the time to teach them how to fight—and _what_ to fight—they would be driven to teach themselves because it was fun.

She sometimes wondered what instincts she’d had when she’d been born the first time. What games she’d played. But she couldn’t remember it.

He kicked one egg and it crumpled in—but something inside stirred. He yelped in alarm, tried to kick it again, and tumbled onto his back. Mothra hurried toward him.

A prematurely born bug scraped and clawed its way out of the egg, hissing, its long eyes glowing red. It swiped at the phosphor mouth.

Mothra splatted a ball of silk against its chest, sticking it inside the remains of its eggshell. And then a second one on its head, and a third on its chest again. The phosphor mouth headbutted its chest until its shrieks gurgled and died and its juices oozed through Mothra’s silk.

And then he ate its head.

He turned to look at Mothra, crunching happily through bone shards. _We protect each other._ He squeakily roared at the dead bug, lights flickering ineffectively up his back plates and ending in a tiny puff of blue; and then he stumbled off to explore the shore.

She was beginning to see why other species liked having a phosphor mouth in their nests.

###

This was how nature worked:

The Godzillas ran. The Jinshin-Mushi hunted. The Godzillas hid their eggs. The Jinshin-Mushi passed over other creatures’ nests, seeking only their adult prey.

The Godzillas fell.

The eggs survived.

###

_I will be asleep for a few days_, she told the phosphor mouth. She put into his mind an image of her cocoon. _I might dream, but I will probably seem dead. Don’t touch me and keep me safe_.

“I’ll protect you, sister,” he reassured her, with a hint of childish giddiness at the thought of the grand battle if he had to keep the promise, but mainly with deep solemnity. His hatchling playfulness had faded fast, along with his early green coloration, shedded like so many scales until all but his belly was a dark blackish-grey; and although he was a _happy_ child—she’d done her best to make sure of that—he was also a thoughtful one. Not curious, not questioning, just thoughtful. Thoughtful—and a little bit skeptical.

_I’m going to have wings_, she told him. She’d told him before—she’d been warning him about her pending metamorphosis for months, not sure how much preparation he needed to be sure he’d still recognize her once she emerged—but a last reminder didn’t hurt. _I can control what colors they have. I can even put some images on them. What do you want them to look like?_

He considered that a moment. He was—of course—skeptical; but she’d never given him a reason to doubt her. “Can you make them look like anything?”

She found herself marveling at the fact that every single word in that sentence came from a different species’s language.

He’d learned to speak from creatures living underwater and on nearby islands, and talked to her now in a hodgepodge of at least twenty languages from seven or eight different species—whatever grammar he felt made his current point and whichever mix of vocabulary he could fit into the shape of his mouth and throat and tongue—and she made up the difference in his comprehensibility by reading his intentions straight from his mind. Most phosphor mouths she’d seen before spoke a heavily accented version of their adopted family’s language. She wondered if anyone would ever be able to understand this one besides her.

_Not quite anything. And I can’t change the shape of my wings. But I can put most things on their surface._

“Do flames!” he said.

Oh. Of course. She’d been reassured by a volcano pter that visited sometimes that _all_ kids had a pyromania phase, but Mothra wasn’t entirely sure that didn’t just apply to pters.

What would flame look like—red, orange and yellow stripes, make them wiggly and end the stripes in points? _I can do flames._

His face lit up.

He watched in rapt fascination as she cocooned herself; and then, as she dissolved into her cocoon, he lost interest—from the outside, it probably didn’t look like anything was happening—and drifted off to gnaw at the picked-clean bones of his parent.

Her mind unraveled and she began to rewrite her body.

###

When he saw her flames, he got so excited that he ran around the island yelling blue light at the sky.

And then—to her surprise—he sat down beside her and started playing with her new thin layer of white fuzz, combing his claws through them. Being combed was new. It felt nice.

“Are you always fuzzy?” he asked her.

_Only if I have a long time to eat and grow before I change_, she said. _If I have to change fast after hatching, I’m thinner and smooth._

“How fast can you change after you hatch?”

_Within a day, if I need to. But I die a lot sooner._

His hands froze.

_Don’t worry. I’ll die a lot, but I’ll always come back. I have eggs all over the world._

“Right.” He felt more uncertain than he sounded. She’d told him this before, but he’d never seen it. He would soon enough.

_You’ll get to see them for yourself soon._ It was why she’d metamorphosed. She’d stayed on this island with the young phosphor mouth for as long as she could. The dead phosphor mouth with a belly full of bug eggs probably meant that the bugs were swarming on the mainlands again, and she didn’t want to expose a young phosphor mouth to that any sooner than she had to—especially when she wasn’t able to teach him to fight, the way a volcano pter or sea serpent could have taught him. The islands were relatively safe; bugs rarely left the main continents. But her eggs would hatch soon if she didn’t go to reset their timers. So she had to go. And he was coming too.

She could tell the thought of her dying made him more uncomfortable than he wanted to face—because he tackled her, butting his snout on her wing in a fake bite and growling threateningly. She squeaked in surprise, but she was used to this game, and she quickly tried to knock him over and silk up his hands before he could get a good grip on her. The first time she got out of snout-butting range, she took off, and he called her a cheater.

They stayed one more night—so he could rest and she could stretch her new wings—and then, the next dawn, they set out from their little island.

###

“What’s your name?” her brother asked. He was completely submerged except for the end of his tail, sticking out of the water like the tip of an iceberg, and his words were half telepathic and half bubbly gurgles.

_Mothra,_ she replied, perched on an actual iceberg nearby. She kept having to shift her feet to keep them from getting too cold.

“That’s your _kind._” He must have been speaking with the volcano pters; that was the term they used for different intelligent species. “I mean your name.”

_My kind and my name are the same. Names are to tell apart multiple members of one kind, and there’s only one Mothra._

He was quiet while he considered that. The tip of his tail disappeared underwater. Mothra took off, rubbing her feet together to warm them up.

_Volcano pters are named after their nests,_ her brother said. He was so deep that Mothra could only hear his thoughts.

_Yes, I know. Sometimes they ask me where I hatched because they want to call me by my nest. My name would change every time I hatched if I did that._

_Is my name Infant Island?_

_Oh._ So that was what he was asking. _No, it’s not. You’re not a volcano pter._ She landed, waiting for the inevitable next question.

_What’s my name?_

He didn’t have one.

And she felt horrible.

Volcano pters named their kind for their nests—the volcanoes they emerged from. Sea serpents named their kind for the specific shapes and colors of the light that glinted off their scales when they curled through the water, as though their names were written across their bodies and could be read in the sunlight. Skull faces were named for the first sounds they made that sounded like words. She had met phosphor mouths with all three kinds of names, and far more besides—some, even, with multiple names. Phosphor mouths didn’t have names of their own; they accepted whatever names were given to them by the people around them.

Mothra, whose name and species were synonymous, who was born over and over already knowing her name—it had never occurred to her that her brother would need her to give him a name.

Once, one of her mutated false reincarnations, small and hard and sharp and mean, unable to enter Mothra’s mind, had insistently pressed itself to her side until she entered its. _Give me a name,_ it had pled, desperate and afraid. _Don’t you know a thing without a name isn’t alive? Give me a name or I’ll take yours._ She had named her nightmare Battra.

She hadn’t named her own brother.

He surfaced before she had a chance to answer him, clutching the sunken egg he’d been rescuing. He looked up at her, head just over the surface of the water, eyes wide and curious, gills half out of water and rippling, and—

_Sweetiefish,_ she told him. _You’re my Sweetiefish_.

She’d come up with the name on the spot. She was relieved when he was delighted.

Mothra landed on the iceberg and her brother—Sweetiefish—climbed up beside her.

He dropped the egg next to her and asked, “Is it still good?”

She lay on top of it, pressing her face to the frozen shell, listening for her dreaming future self inside.

Nothing.

_No,_ she said. _It’s dead. It probably isn’t even good to eat._

“Oh.” Sweetiefish radiated disappointment. Mothra rolled the egg off the iceberg and back into the water.

_Come._ She lifted off and fluttered toward the island that the egg had rolled off of. Sweetiefish sank back underwater and followed her. _We’ll make my next nest in a hill where a glacier can’t carry the egg away. We’ll have to stay here a few days so I can lay a new egg._

_Can I bring you food?_

She’d told him that she needed to eat a lot when she was going to lay an egg, and plantlife was sparse and small this far north.

_Just don’t go farther than I can hear you._

And he didn’t.

But she wouldn’t be able to keep him so close forever.

###

“Evolution” is defined as a change in the inheritable characteristics of a biological population over successive generations, as expressed in the genes passed on from parent to offspring.

###

Mothra traveled between her nests more slowly, now that she had a juvenile phosphor mouth tagging along. They moved fast over water, where Sweetiefish could easily swim fast enough to keep up with her; but more than once she had to leave him behind somewhere safe for a day or two so she could reach eggs deep in continents.

She was afraid to leave him alone for too long. The world wasn’t overrun with bugs like she’d feared, but it was still half-barren from the last plague, and the remaining starving bugs crawled around looking for food. Sweetiefish was younger than their usual prey and wouldn’t make a good meal for many bugs or good incubator for many eggs; but he was healthy and strong, and had a tendency to start flashing threats at any unidentified moving object that was larger than his eye. She didn’t know if he knew to be afraid of bugs. To this day he still liked stepping on and popping round hollow things, but that wouldn’t be much help against a full-grown bug.

Once, she hatched alone.

She didn’t know what had happened to her last incarnation; all she remembered was seeing a bug in the sky heading in the direction she’d left Sweetiefish, and frantically resetting the egg’s timer to hatch immediately before tearing off after it. If her last incarnation hadn’t come back to re-extend the egg’s timer, then she’d died fighting the bug. But had she _won?_ Was her brother okay?

She forced herself to metamorphose in a few hours and came out hungry and frail and small, but fast and sharp. She tore off toward the coast.

She found herself—her last self— and she found the bug, both dead. They’d only been dead for a few days. They hadn’t made it to the coast—but the bug might have signaled its siblings. She stopped long enough to eat her previous incarnation’s corpse for strength, leaving the fire-patterned wings, and raced on to the coast.

He was where she’d left him, curled up just off shore, letting the surf wash over him and over him, nervous in his aloneness. The moment he spotted her, he clambered to his feet, shaking himself dry as he ran onto the shore to meet her. He wanted to know why she’d taken so long. He wanted to know why she looked so small and weak. Was she okay? Did she get in a fight? Was she hungry? Why were her wings green now?

Because she hadn’t wanted to be seen as she raced over the forests back to him.

She relocated all of her eggs to coastlines—bays, islands, straits, deep river deltas. They would be more vulnerable there, where aquatic ovivores would have an easier time crawling ashore to get at them; but it meant she’d never have to leave her brother behind.

She rewrote her eggs so that all of her future selves would place their eggs on the coast, too.

###

Mothra lost more and more eggs now. Each time she made her rounds, she had to stop for long periods to form and lay another egg—which meant she slowed down, which meant she couldn’t visit her eggs as often. Laying so many eggs in one lifetime wore her out. Sweetiefish asked if she could lay them less frequently, then pleaded for her to stop; and when she said she couldn't—her future survival depended on it, even if it meant threatening her short-term survival—he lurked nearby, whining unhappily as she strained to grow another healthy egg.

Her lives were shorter. Two eggs in a row hatched mutated and sharp. She had to replace more and more eggs. Maybe she should just have fewer nests and visit them more often.

“I’ll protect your eggs,” Sweetiefish said.

_What do you mean?_ Mothra had felt him brooding on the problem of her eggs for days now. He was old enough to do that now, _brood_ rather than just _think_. He wasn’t quite as large as the typical adult phosphor mouth, his belly was still a pale foggy grey, and his back plates were still mostly rounded—but the plates were just starting to develop their sharper points, and he had an adult’s roar.

Adult phosphor mouths, she’d learned from other adoptive families, visited their home nests, but usually lived solitary lives in the ocean. She’d wondered—and worried—about when he’d decide that it was time for him to go. She’d lived a dozen lives next to her little brother. She wasn’t ready for him to leave.

But it seemed _he_ was ready. “Your eggs are eaten because nobody’s scared to eat them,” he told her. “Even if you’re there when someone attacks, all you do is tie them up or get poison scales on them that knock them out a few minutes. Of course they come back and try again when you’re gone. If _I’m_ there, I can kill them.”

Mothra winced at the thought of it. She knew he could—she knew he _had_—but all the same, she hated the thought of killing. _She_ was expendable; she could die and die again and forever come back. But everyone else—for them to die meant a person vanishing from the world forever. No one else had eggs that carried their next selves. They would not rise again. And the thought of that, of people around her _ending_, made her ache.

But Sweetiefish was determined. And if she kept losing eggs at this rate…

“I can swim between all your nests now,” he insisted. “I can make a route like you do. I can check on them all the time. If I catch anyone trying to eat one, I can kill them. If they’ve _already_ eaten one, I can track them down and punish them.”

_But how will I know where you are?_ she asked. _What if you get in trouble?_

“I can protect myself if I’m in trouble.”

_We protect each other!_

He balked at that. “You can hear me, can’t you?” he said. “Won’t you be able to hear me if I’m in trouble?”

She thought about that. _From across a continent? Across the world?_ she asked. _I don’t think I can. But—maybe I could_.

He began his patrols. She followed along—which slowed him down, but she promised it would only be until she could adjust her eggs just right.

It took three tries. The first time she ruined her hearing completely. The second time, she could hear far too much, much too far, and ultimately it ruined her hearing again. But the third time, she got what she wanted: after metamorphosing, when she closed her eyes, when she focused hard, no matter where she was, she could hear his heart beating and the distant rumble of his mind.

###

Mothra heard Sweetiefish scream from halfway around the planet.

She tore off as fast as she could. She was grateful that she was currently fully grown; but she wished she was more aerodynamic. Her fuzz dragged against the air. She was too slow. She needed to get to him faster, faster, faster.

It was over by the time she reached him. She didn’t know what had attacked him; just that she could see the blood it had left behind long before she landed, and she wasn’t sure how much of it was from the attacker and how much was from her brother.

She could hear his thoughts long before they were close enough to speak: _You’re wearing the fire wings again. The ones you made for me._

_I like the fire wings._ She tried not to let him feel her terror.

His neck, his chest, his arm were lacerated. The bleeding had slowed, but it started again every time he tried to move. He lay on his side in front of her burrow, blocking it with his body.

_Who did this?_ She landed next to him.

“Three-headed freak,” he growled. “Flying. Lightning. Couldn’t understand him.”

She went cold with terror. She knew them.

She’d seen a meteor crash down, tracked it, and found three creatures sharing one body tugging themselves out of it like they’d hatched from it. She’d felt that they were like her—that their minds could speak to other minds. She’d tried to greet them. She’d tried to ask their name.

They had no name. A thing without a name isn’t alive.She’d feared them then.

She’d felt _their_ fear of _her_, and they’d fled.

She hadn’t seen them since.

Were they hunting her eggs now? Were they destroying her future incarnations? Had they attacked her brother just because she’d frightened them?

She ran her legs over Sweetiefish’s wounds uselessly—even if she cleaned them and kept him safe, she didn’t know if they could heal before he died.

Maybe he couldn’t heal himself. But…

_Let me in! I need to get to my egg!_

He could only shift a little bit, rolling on his side—it looked so much like the pose his parent must have died in, torn open on yet another island between her burrow and the shore—no. No, no, she wasn’t going to let that happen. She crawled into her burrow and clung to her egg.

She could rewrite herself.

In her cocoon, she could rebuild herself from dust and liquid into a new body, a whole living body. She could shed poisonous scales from her wings that paralyzed her targets. What if she made a potion instead of a poison? What if instead of paralyzing whoever she shed them on, she gave them the ability to do what she did—to regrow from dust and liquid, to regrow from torn flesh and blood—to heal wounds instantly, to be filled with life?

She only had one chance.

She clung to her egg, forehead pressed to the shell, not so much rewriting the future incarnation inside as tearing the existing writing into fragments and sticking it back together in new ways, please, please, please let this work—

She set the egg to hatch immediately. The incarnation inside didn’t waste a moment gently shifting around in the shell, but rather _fought_, struggling to get out so they could save their brother. She waited for the incarnation in the shell to make the first crack, and then tore it open the rest of the way herself, ripping her duplicate incarnation into the world.

It hurt to be ripped into the world. And it would hurt to cocoon herself so fast. But they didn’t have a choice.

“What… are you…?” Their brother’s voice was weak and gravelly. The grown Mothra had been helping the younger spin her cocoon—every second counted—but at Sweetiefish’s voice, she scrabbled to the mouth of their burrow to reassure him.

_It’s okay,_ she told him, butting her head against his and hoping he couldn’t feel her fear. _We’ll save you. Just hold on._

“'We’?” he asked. “No, don't—I got hurt saving your egg, don’t make it mean nothing—”

_I’d rather have you than one egg,_ she said angrily. _Anyway, it’s too late. I already did. Just hold on a little bit longer._

The moment she felt her younger incarnation’s mind stir again inside the cocoon, she scrambled back down, helping to tear it open and set her free. She was the spindliest and weakest that Mothra had ever been, shaky on legs like twigs, a shriveled abdomen that would never lay eggs, a head almost too heavy to lift. The elder had to support her as they climbed up to the opening of the burrow. Please, please, please—

_This should heal you._ Feebly, the younger Mothra brushed her wings over their brother, shedding the loose scales on him.

He flinched, and looked weakly up at them. “Your poison?”

_It’s not poison anymore_. It shouldn’t be poison. _I rewrote it. It’ll help you. I promise_.

_It stings._ He squeezed his eyes shut, jaw tight.

_I’m sorry. Just hold on._

They could feel his flesh heating up under the scales; they could see the scales working into his hide as they crumbled apart, smaller and smaller. They could very nearly see his wounds begin to heal. But it wasn’t enough. He needed more.

The elder Mothra ripped off the younger’s wings.

Sweetiefish’s eyes shot wide open as her pain echoed through his mind. He roared feebly. _What are you—?!_

_It’s okay. It’s okay. Just wait._ She shredded and crumbled the wings, grinding them into his wounds, ignoring his screams—and then, when the wings were gone, the body of her younger incarnation. She endured the pain, trembling.

This was one of the only times she would remember how her own death felt.

There was nothing left to give. Her brother’s flesh was burning to the touch. He was glowing red. But he was healing—wasn’t he? She could see his wounds closing. She could feel his strength returning to him.

Until, finally, half wild with pain, he lurched to his feet, stumbled away from her burrow, and launched himself into the ocean. Steam billowed out of the water around him.

It was several minutes before she could get anything from his mind but overwhelming pain. _Are you okay?_

_I’m alive._

That was good enough.

_You got rid of your poison,_ he said. _How will you protect yourself?_

_I’ll put it somewhere else._ She could make a stinger. Turn the poison into a liquid venom.

_You died for me._

_It isn’t the first time,_ she said. _You’re my Sweetiefish. I’ll die a million more times to save you. Just make sure I can come back a million and one times_.

He crawled back onto the shore, stood wearily, and trudged up to her. “Always,” he said. “We protect each other.”

_Always._

###

“Evolution” is defined as a change in the inheritable characteristics of a biological population over successive generations, as expressed in the genes passed on from parent to offspring.

Over several generations, rewriting the genes of her eggs one by one to make sure she could better protect Godzilla, Mothra evolved herself into a sister.

###

Humans were the smallest intelligent species that Mothra had ever seen. She adored them. Together, they built structures out of wood and stone the size of a normal creature’s nest. Even as large as one of _her_ nests.

She wondered if they’d build nests for her, too.

She visited the human cities with the largest buildings—she liked the ones that looked like free-standing hills with flat sides and even corners—and in each city, found twin sisters, and modified one so that she would be like her: able to birth her own replacement without a mate. She guaranteed that her chosen would also birth twins, so that they could share the heavy mental load of her vast mind. Life, she had found, was so much easier with a sibling.

Then she waited for a new generation to be born and grow; and with the twins as her representatives, she spoke to the humans: she told them that she would like their help to build a stone nest around one of her eggs. She would help them in the construction, and she would offer their city her protection if they accepted. If they didn’t want to, she would respect their decision.

Some didn’t accept. She left them in peace.

But most accepted.

And when others came along to threaten the civilizations that harbored her eggs, as the divine moth had promised to the humans, a creature with a scream like blue fire rose from the ocean to defend them. And above him, like sunbeams through the storm, the moth herself appeared to fight alongside him, with the eyes of her warrior emblazoned upon her wings.

**Author's Note:**

> Original post available on [tumblr](https://ckret2.tumblr.com/post/187157121077/cuckoo). Comments/reblogs there are very welcome (as are comments here)!
> 
> References to Godzilla media outside the MonsterVerse movies:
> 
> \- The quote at the beginning is this fic's inspiration. In GvMGII, a Godzillasaurus egg is found in a Rodan nest, and Rodan treats it like a sibling while adult Godzilla treats it like his child. Both of them fight to protect it—even after Rodan realizes it's a different species. The idea of Godzilla's species being like cuckoo birds and being fully embraced by their adoptive families absolutely delighted me.  
\- The MUTOs are referred to as "Jinshin-Mushi" in this fic because that's their official name from the comic Godzilla: Aftershock. It's a more obscure name but, like, it also isn't MUTOs, which is a cruddy name for a species.  
\- I'm fond enough of '98 Zilla laying eggs parthenogenetically that I apply the same headcanon to other versions of Godzilla because no one has the power to stop me from doing so. Which is why there's no references to Godzilla's "other" parent or a thought from Mothra about trying to look for one. This Godzilla conceived and laid the egg alone. (Godzilla wonders about both a mother and a father when he hatches not because he expects to have two biological parents, but because baby Godzillas all hatch in the nests of other titan species, which, depending on the species, _do_ often have two parents.)  
\- In KOTM, Ilene Chen shows a picture taken on Infant Island of her relatives next to some giant friggin bones. Mothra, being a moth, doesn't have bones. So they're from Godzilla's parent.  
\- Mothra's portrayed as both telepathic and as reincarnating because of prior continuities. (She's portrayed as reincarnating in KOTM too, but basically in an easter egg in the credits.) The mechanism of her reincarnation is never really explained, so I decided I wanted to steer toward a sciency explanation rather than a strictly spiritual one.  
\- Her reincarnation that "couldn't lay eggs" that she uses "he" for is Mothra Leo, with his determination to defend his future reincarnations' eggs more fiercely since he can't lay any replacements being used as the justification for why Mothra Leo's got a billion powers compared to Mothra lmao. So in this continuity, Mothra, Mothra Leo, & Battra are all Mothra (just reincarnated into slightly different bodies).  
\- Godzilla is green as a juvenile because of Little Godzilla from Heisei and because of Godzilland Godzilla.  
\- Mothra's first body—fuzzy with "fire" wings—is supposed to look more like Showa or Heisei Mothra. Her KOTM appearance is one of her emergency fast metamorphoses in order to go into battle.  
\- In MonsterVerse, with Mothra having eggs all over the place, she's got no reason to view Infant Island as her "home." But I _like_ it as her home; which is why I put it as where Godzilla hatched. He anchors her to the island. (Also giving her a reason to associate the island with infants and pass that association on to later human inhabitants.)  
\- "Volcano pters" are Rodan's species, "sea serpents" are Manda's, and "skull faces" are skullcrawlers.  
\- Mothra's paralyzing poison scales originate in Showa.  
\- The "route" that Godzilla travels to check on Mothra's nest sites is intended to be the global "territorial routes" he's referred to as using in KOTM—which is why moving her eggs near coasts was necessary.  
\- Ghidorah's arrival in a meteor comes from his Showa origin.  
\- Ghidorah having mental abilities similar to Mothra's comes from Heisei, where dorats (the creatures that mutate into King Ghidorah) are described as empaths. Ghidorah freaking out at making contact with another telepath comes from the fact that over the course of Showa and Heisei, King Ghidorah gets telepathically mind controlled by just about every frigging species he runs across.  
\- Mothra deciding to relocate her poison into a stinger comes from the hypothesized-but-unconfirmed theory that Mothra stabbing through Rodan's chest stopped him not just because of the wound itself, but because it had some sort of paralyzing venom.  
\- I'm hella iffy about any story that even _implies_ "humans make pyramids because they were taught and/or inspired by some Superior Species"; so when we saw that Mothra's egg was in a pyramid, I decided I wanted it clearly established that this was because humans had invented pyramids and she thought they were so cool she asked to get some too.  
\- In prior continuities Mothra has Shobijin, tiny twin fairies that serve as her advocates/representatives; in KOTM, the Chen family is hinted to be like human Shobijin; so I wanted to make the connection explicit and tie their line of female twins more directly to Mothra.
> 
> And that's THAT. Comments are welcome if you want to leave any!


End file.
